1. Technical Field
This invention relates in a helmet for communication, and it is related to the helmet for communication in which an optical microphone is built.
2. Description of the Related Art
To perform a communication in the situation that a helmet is worn, a microphone for the communication mounted inside the helmet may be used. As this type of microphone for communication, a close-speak type microphone and bone conduction type microphone, and so on are known. At any rate, a microphone that may decrease an outside noise is required.
FIG. 9 shows the section structure of the helmet to explain the wearing state of the conventional microphone for communication. Inside structure of the helmet 60 is formed so that a head 65 may be fixed firmly by the right chin liner 61 and a left chin liner 62. Around the mouth, a space (cavity) 64 is formed, and this cavity 64 is partitioned by cloth 63. Then, when a close speak type microphone 71 is used, it is fixed on the front of the mouth firmly, and mounted so that the microphone 71 may receive the voice of the speaking person through the cavity 64. When a bone conduction type microphone 72 is used, it was installed in the location where it stuck to the head 65 firmly in a part of the right chin liner 61 or the left chin liner 62, and mounted to transfer the voice conveyed by the bone conduction in the microphone 72.
Like this, with the helmet containing the conventional microphone, the microphone of the close speak type is fixed on the close location to the mouth in order not to be affected by the influence of the noise of the surroundings and to improve S/N ratio, or to pick out the sound wave by bone conduction in order not to pick out the noise of the surroundings.
However, with the conventional microphone stated above, the decrease of the noise depends on the wearing state of the microphone and the effect on a noise decrease is limited. With the conventional helmet for communication shown in FIG. 9, the noise decrease level was no more than 6-7 dB. It is an object of this invention to solve the problem, by drastically raising a noise decrease level, to provide a communication helmet comprising a microphone that has high sensitivity and wide-band even when the noise level of the surroundings is high.
The helmet for communication in this invention is a helmet that installed microphone inside the helmet so that it may be located in the neighborhood of the mouth of the speaker, wherein the microphone is an optical microphone comprising, a diaphragm which oscillates by the sound pressure, a storage container that stores the diaphragm and has a first opening and a second opening provided in a symmetrical location and confronting the diaphragm, a light source which irradiates a light beam in the diaphragm, and a photodetector which receives a reflection light of the light beam irradiated in the diaphragm and outputs the signal coping with the oscillation of the diaphragm, wherein the optical microphone installed on a mount being slanted by a predetermined angle with the mount so that an arrival sound wave may enter equally in the first opening and the second opening, and wherein the mount is installed to have a space so that an outside sound wave may enter equally in the first opening and the second opening. The helmet for communication of this invention may further comprise an angle alignment means that varies an installation angle between the optical microphone and the mount. In the helmet for communication of this invention, the mount may be installed to be parallel with the optical microphone.